Feed mechanism for a developing apparatus



2,186,637 a 1/1940 o en etal.

"United States Patent Inventor Borge Simon Nielsen Skolegade l9, Copenhagen Yalby, Denmark Appl. No. 666,683 Filed Sept. 11, 1967 Patented Oct. 20, 1970 Priority Sept. 9, 19 66 Germany FEED MECHANISM FOR A DEVELOPING APPARATUS 4 Claims, 3 Drawing Figs.

.u.s. Cl .L 95/94, 355/100 1m.c1 G03d3/l2 Fieldul' Search 95/89(Miscellaneous),

SQ/(Feed), 89/(L0m), 94; 355/92, 93, 99,100; 226/(Considered);27l/(Considered) References Cited I UNITED STATES PATENTS 3,112,685 12/1963 F1uke..J'..-..I.'...'.. 05/89 -3,257,927 6/l966 DeBelder 95/89 FOREIGN PATENTS 1,146,365 .3/1963 Germany Primary Examiner-Norton Ansher Assistant Examiner-F red L. Braun Att0rneyV Vaters, Roditi and Schwartz ABSTRACT: A developing apparatus consisting of a processing bath, a photosensitive sheet feeding mechanism, guide elements for guiding a pair of sheets through the bath,

and squeegee rollers at the exit end of the bath for removing 1 excess processing solution from the sheets. The feeding mechanism includes a pair of feed rollers, a drive motor, a drive gear, an idler gear, and a lost motion device for connecting the drive gear to the idler gear. The idler gear, is coupled to the feed rollers for driving the rollers in response to operation of the drive gear. The apparatus has an independent drive member which engages the idler gear and may be manually operated to advance one of the sheets being processed by a predetermined length prior to advancement of both of the sheets through the processing bath.

Patentd 0.120, 1970 Shee t g of 2 i .2: l g:

T 2;; 1m HWM RH mizww QN [Q h FEED MECHANISM FOR A DEVELOPING APPARATUS, BACKGROUND'OF THE INVENTION Frequently, and in particular in the manufacture of offset printing plates, it is imperative that the image to be transferred is placed exactly on the positive coated sheet. Since offset printing plates are rather costly, they do not permit a number of tests with consequent discarding of unsatisfactory copies,

' wherefore it should be aimed at adapting the apparatus in such printing plate in the printing machine being very difficult and circumstantial. The difficulties arise thereby that during the passage of the .two sheets through the copying bath they will be displaced more or less in relation to each other, and where an offset printing plate is involved, such a plate is of substantially greater length than the negative sheet and so must have a substantial lead in relation to the sheet through the bath.

.Hitherto known apparatus of the aforesaid kind have been I unable to meet these requirements, there having been either excessive waste, or difficult and time-consuming adjustment I and alignment.

The invention relates to an apparatus for manufacturing photocopies, more particularly offset printing plates, by the method of diffusion, in which an original laid together with a negative coated sheet is exposed, the exposed sheet being then laid together with a positive coated sheet or offset printing plate and subsequently together with, but spaced from the latter, passed along guide channelsthrough a copying bath to a pair of squeezing rollers, the guide channels for the sheets being of minimum height compared with the thickness of the sheets and separated at the feed end by a plate-shaped divid ing member which extends between local thin portions provided in a pair of feed rollers which are connected with a driving mechanism having two consecutive phases of movement.

By this design the twocoated sheets are guided in practically exact manner through the bath, since the low channels guide them so safely that any casual displacements of the said sheets are eliminated, and it is therefore possible to reckon with a constant predeterminable displacement depending upon the location of the sheets at the start. The displacement necessary for this purpose is readily provided by means of the driving mechanism, which in one phase may move one sheet into its leading position and subsequently move the two sheets through the bath as a combined unit.

in accordance with the invention the lead is preferably provided thereby that the arrangement of the pair of feed rollers is such that a predetermined length of one coated sheet may be introduced between them and be retained in that position. The other coated sheet may then simply be placed in position adjacent to the mutually abutting generatrices of the rollers, by which the sheets have the predetermined displacement at the moment ofthe start.

An embodiment of an apparatus according to the invention will now be described with reference to the drawing, in which FIG. 1 is a perspective view of the apparatus, j, FIG. 2 is a section through the left-hand end of the apparatus shown in FIG. 1, viewed from the side and on a larger 'scale, and

' placed on the glass plate together with an original for exposing the sheet. During the exposure the sheets are retained by a lid 3 hinged along its rear edge to the box 1 and having aframe 4 of resilient rubber and a plate 5 of comparatively thin rubber glued tothe frame. The space formed between the plate 5 and the lid 3 inside the frame 4 communicates with the outer atmosphere, whereas the space between the rubber plate S and the glass plate communicates through a pipe 6, which simultaneously constitutes the hinge joint of the lid, and a tubing 7 with an electrically driven vacuum pump mounted in a part 8 of the-box.

being the differential pressure between the pressure exerted by the outer atmosphere and the vacuum in the hollow space. Exact copies are thereby obtained.

The lid 3 may be held in position against the glass plate 2 by means of a clamp 9 engaging a swingable hook which is mounted on a toggle joint 10 connected with a membrane servomotor 11, which also communicates with the vacuum pump and is adapted to pull the hook and consequently the clamp 9 down so as to hold the lid and the plate 5 firmly pressed against the glass plate 2.

A rail 12 mounted along the front edge of the glass plate 2 serves as an alignment rail for the sheets when the diffusion copying is to take place. As is known, the negative coated sheet, after being subjected to exposure, is laid together with the positive sheet which, for example, may be an offset printing plate, and is passed through a diffusion bath. To provide is fully automatic in operation and provided with a pair of feed rollers 14 extending transversely of the longitudinal direction of the apparatus, which affords a very convenient operation of the apparatus. When the lid 3 is opened after the exposure, the negative sheet may, as mentioned, be laid together with the positive sheet and be abutted against the rail 12, the two sheets being subsequently passed to the left (FIG. 1) to the pair of feed rollers 14.

The diffusion bath 13 has, in addition to the feed roller pair 14, a pair of squeezing rollers 15 which are parallel with the roller pair 14 and driven together with same by means of a chain or belt 16 passed over a drive wheel 17, which is connected with an electromotor M, for example the same 5 motor driving the aforesaid 'vacuum pump.- The drive wheel 17 is in mesh with a gearwheel 18 freely mounted on a shaft 19 fixed in the box 1 and provided with an inwardly facing, tubular extension 20 (FlGS. 2 and 3), in which there is a slit 21. The tubular extension is mounted on a collar of a gearwheel 22 lying therebehind and likewise freely rotatable on the shaft 19. The said collar has a radial driving stud 23 located in the slit 21. The gearwheels l8 and 22 are thus movably connected with each other, the connection having a backlash corresponding to the length of the slit 21. The slit extends to theend of extension 20 to permit easy withdrawal and replacement of the gearwheel 18 by another gearwheel with a slit 21 or of dif ferent length so as to provide a longer or shorter backlash.

The gearwheel 22 is in mesh with a gearwheel 25 freely rotatable on a permanent shaft 24 The upper part 26 of the gearwheel 25 projects up through the rail 12 and may thus be acted upon manually. The gearwheel 22 is further in mesh with a gearwheel 27 mounted on the shaft of the lower roller l4.'

The diffusion bath consists of a liquid trough 28 with developing and diffusion liquid. In the trough are mounted guide means in the form of vertical plates 29, 30 and 31, ar-

ranged behind each'other if viewed as in FIG. 2. The said plates form in combination two curved guide channels 32 and I trough and having an extension upwards and to the right to.

form a horizontal tongue 35 projecting between the rollers [4 in a turned-down neck 36 provided on same.

The apparatus is operated in the following manner: An unexposed, negative coated sheet is laid together with an original aligned in relation to the coated sheet in such manner that the letter image is correctly positioned at a predetermined location of the said-sheet. The two sheets laid together are then placed on the glass plate 2, and the lid 3 is lowered so that the plate 5 is caused to rest on the glass plate, the lid being retained at a slight pressure against the said glass plate, after which a pushbutton 37 is activated. This will start the vacuum pump, and the servomotor is actuated so that the hook (not shown) is caused to engage the clamp 9, pulling it downwards, by which the plate 5 is pressed firmly against the glass plate 2. At the same time the hollow space between the plate 5 and the glass plate is evacuated, by which the aforesaid intimate contact between the sheets is provided.

The apparatus is now adapted in such manner that the illuminants are switched on automatically and remain lighted for an interval corresponding to an exposure time preset on a clock 38. Upon completion of the exposure, the vacuum is automatically terminated, so the clamp 9 is released and the lid 3 tilts back by spring power into the open position indicated in FIG. 1. At the same time atmospheric air is admitted into the space above the glass plate.

After exposure, the original is removed, and the negative sheet is laid together with a positive sheet, for example an offset printing plate consisting of an aluminum plate of substantial length in view of its arrangement in the offset printing machine, and it would be irrational to produce the negative sheet of a corresponding superfluous length, wherefore coated sheets of substantially shorter length are used so that is necessary to align the two sheets in relation to each other, which must be done with very great accuracy since the image to be transferred has to be exactly and correctly positioned on the printing plate because it is impossible or very difficult to make an adjustment of the printing machine.

In the apparatus according to the invention, the necessary longitudinal displacement of the two sheets in relation to each other involves, however, no difficulty, the requisite lead of the positive sheet being provided in the following simple manner:

The positive sheet or the offset printing plate, respectively, is passed towards the roller pair 14, continually guided by the rail 12, and is brought into contact with these rollers beneath the dividing plate or the tongue 35. In the starting position the driving stud 23 is located in contact with the left-hand end wall 39 of the slit 21. The gearwheel 25 is now, owing to activation of the part 26, turned in counter-clockwise direction, as a result of which the gearwheel 22 turns in clockwise direction, the stud 23 moving through the slit 21 until stopped by striking the right-hand end surface 40 of the slit. Since the gearwheel 18 carrying the slit is in mesh with the driving wheel 17 which is blocked, there is no possibility of further movement. The gearwheel 22 is furthermore driving the gearwheel 27 and consequently the pair of rollers 14, by which the positive sheet or the offset printing plate, respectively, is passed to the left in FIG. 2 as much as corresponds to the length of the slit 21 and is retained there.

The negative sheet is subsequently passed above the plate 35 and brought into contact with the rollers 14, and the apparatus is now in its starting position in which the positive sheet has a lead corresponding to the length of the slit 21. The driving motor is now started by activation of a pushbutton 37, and the driving wheel 17 will then cause the roller pair to rotate and likewise rotate the gear wheel 18 which will at first rotate as much as corresponds to the length of the slit, after which the end surface 39 will press against the stud 23 and turn the gearwheel 22 carrying same. As a result, the gearwheel 25, the gearwheel 27 and consequently the rollers 14 are caused to rotate. By means of the rollers 14 the two sheets are now passed down through the guide channels 32 and 33 and through the bath up to the squeezing rollers 15 which pass the sheets out of the apparatus.

Owing to the height of the guide channels 32 and 33 being reduced as much as possible random displacements of the two sheets in relation to each other will be practically eliminated, and the displacement inevitably arising because the guide channels are placed above each other is compensated by the design of the slit 21. The aforesaid backlash, which is provided by means of the stud 23 and the slit 21, and which gives the positive sheet a predetermined lead in relation to the negative sheet, affords compensation both for the said displacement that is determined by the design of the apparatus and for the desired distance between the leading edge of the positive sheet and the leading edge of the negative sheet. Variations in the said lead is provided by replacing the gearwheel 18 with the slit 21 by another gearwheel having a slit of a different length.

As will appear from the foregoing specification, the apparatus is, owing to the arrangement of its individual components and its design, very convenient and easy to operate, and a perfectly exact location of the printed image is obtainable, even with operation by an unskilled staff and without special care. Thus, a saving in time and material alike is obtained, the number of unsatisfactory copies being reduced to a minimum.

lclaim:

1. Apparatus for making photocopies by the diffusion transfer process, said apparatus comprising means for aligning an exposed negative sheet and a positive, coated sheet in superposed relation, feed rollers for advancing the sheets, a developing bath means in which the sheets are advanced by the feed rollers, guide means in said bath means having a respective channel for the passage of each sheet, a pair of squeeze rollers outside the bath means for receiving the sheets therefrom under the drive of the feed rollers, a dividing plate extending in front of the feed rollers for guiding each sheet to the feed rollers and into its respective channel in the guide mear s, and drive means for said feed rollers to produce preliminary feed of a predetermined length of one sheet introduced into the feed rollers and subsequent feed of both sheets together, said drive means comprising a drive gear, a driven gear in mesh with the drive gear, an idle gear coupled to said feed rollers in driving relation, means for independently driving the idler gear. and lost motion meansconnecting said driven gear and idle gear to permit the independent driving means to rotate the feed rollers via the idle gear by a particular amount corresponding to the feed of a predetermined length of said one sheet when the latter is positioned at said feed rollers.

2. Apparatus as claimed in claim 1 wherein said independent driving means comprises a manually operable gear in r'r'ie'sh witrrsaiatalegear. i

3. Apparatus as claimed in claim 1 wherein said lost motion means comprises a pin and slit connection between the driven gear and the idle gear.

4 Apparatus as claimed in claim 3 wherein said slot is on the driven gear and the length of the slot determines the mag nitude of the'predetermined length of said one sheet which is preliminarily fed, said driven gear being replaceably engaged with said idle gear. 

